From digest.v7.n734 Tue Dec 9 14:07:03 1997
From: "Rob Levinson"
Date: Tue, 9 Dec 1997 09:51:47 -0500
Subject: Re: B&B Exhaust sounds (and remedying other loud cars) **Rob
Dave Quinn (and Jeff Lee) wrote:
>Subject: B&B Exhaust sounds
>To all who me asked to forward them suggestions I got for reducing the
>loudness of the exhaust in the interior of the car, most suggestions
>referred to padding the trunk from the article in Roundel.
>I had the same problem after spending more than $700 for a B&B exhaust.
>The solution I found was to stuff two stainless steel sponges into each
>of the exhaust outlets
I have used and reccomend a product called "DynaMat", designed
to improve car audio performance by absorbing road noise. It's an
asphalt-based film, (depending on which strength) approximately 1-3mm thick.
It's sticky on one side and requires attachment directly to sheetmetal. In
your trunk this is easy - pull up the carpet, stick and hit with hair dryer.
Inside the car is obviously a little more difficult - carpet, seats, door
panels. It *IS* heavy stuff - you M3 LTW guys would want to avoid using it.
The benefits are unbelievable (if used correctly)... all other things being
equal, after driving a car with DynaMat, the same car without will sound
like the windows are open.
I used this stuff in my last (of three) RX-7 Turbo .
Running a straight-through racing exhaust (open mufflers, no cats, header
pipe) this car was *loud*... truly, Hell hath no fury like a turbo rotary
uncorked! It was livable for short hops (and smoky burnouts and 145-mph
runs...) but a 100-mile commute forced me to decide; I could either 1)
ditch the trick parts, 2) give up my hearing, or 3) use Dynamat. Dynamat
won, and I was thrilled with the car. After replacing the cats in order to
sell it, the car was quieter (inside) than a stocker.
Dynamat should be available through high-end or custom car audio
shops, Crutchfield carries it, but the best deal might be from any
mail-order place advertsing in "Car Audio" magazine. Depending on which
grade you use and how big your car (Z3 or 750iL...) it might cost you
$150-$250 and a day spent stripping out your BMW.
- - Rob Levinson
'85 535i Turbo -> http://www.wholesalewebdirect.com/rob/callaway.htm
"Interesting BMWs" web site ->